Electric follow-up switch



May 7, 946. G. OLAH 2,400,018

ELECTRIC FOLLOW-UP SWITCH v Filed Jul/y 14, 1945 s sheets-sheet 1 .Nl KQ. f w

HIIIIHIIIHI minimum' Ma! 7. 1945 I G. oLAH f 2,400,018

ELECTRIC FOLLOW-UP SWITCH Filed July 14, 1945 5 sheets-sheet 2 May "7 1946. G. OLAH 2,400,018

ELECTRIC FOLLOW-UP SWITCH Filed July 14, 1911";v 5 Sheets-Sheet 5 DN w N w C lictcntcd May 7, 1946 i e aLEc'rarcroLLowUr sw'rrcn A George Olali, London, England; assigner t Preeislon Developments Company Limited, London, England, a corporation otGreatllrltaln Aspiration .muyr 14, 194s; serial No. 494336 In Great Britain anni 29,1942 t rlhis invention relates to the arrangement of contact carrying members in switch gear' and more especially to types of switch gear inwhich the amount oi displacement of the movable memser is not determined solely by the requirements of the switching operation but bears a definite relationship to an interconnected displacement in the mechanism of whichv the switching member Switching devices oi this kind are used extensively in various types of electric control apparatus particularly as limit switches, selector switches and follow-up switches.

More particularly this invention concerns switching devicesof the Ltype referred to above in which a plurality of contacts `is to be l,controlled by one movementgof the movable member.

In switchingvdevice's of the type referred toit is most convenient 'and natural to usecontact surraces at the same time as limiting or transmitting members for mechanical'xnovement. In fact any arrangement in whichthese two functions are separated would requir'e'extreme care in manufacture and adjustment to'obtain any contact at all and even under most favourable vconditions the contact pressure and therefore. alsol the contact resistance of an individual contact would be uncertain. I u l in many switching device of the general type it customary to arrange cooperating contacts to slide on each other while performing the switching operation. In such casesitheiswitchlng of a plurality of circuits presents no dii'iiculties. The contact pressure bears norel'ation tothe switching movement.

in another type of construction the. contact carfrying members are all mounted resiliently on the 'main movable or stationary member. In this .case there is also no particular 'difilculty associated with the number of `contactstc'rbe operated simultaneously. The contact pressure is determined by the amount ofdisplacement in the switching motion' and'distributed according to resilience of the mounting ofthe individual members.

Both of the last mentioned switch designs .are not easily applicable to devices to. which this in vention applies, whereco'ntacts must .be made and broken fully and solely upon the occurrenceoi a. definite and limited displacement of the movable member.

1t is the purpose ci the present invention to provide simple and effective means for switching ci a plurality of contacts by a strictly controlled and limited movement, producing equal contact pressureonall contacts and to obtainlthis ifesult without requiring undue accuracy in manufacture and"adjustment,l f According tothe presentinvention in a switching device which performs the closure and interruption of at least two pairs of cooperating 'contacts fully and solely controlled'bya deilnite and limited relative displacement between va movable anda stationary member and inv which-the contact surfaces coincide with limiting ortransmitting surfaces for the said relative displacement an additional member-is provided which is freely i `floating between the two aforesaidA members and vice. i

which carries at least one each of the several pairs of contacts controlled by the In order that thevinvcntion may be better understood and applied it willnow be described in detail in its embodiment in severaltypes of follow up switches with reference to the accompanying drawings, in which Fig. 1 shows diagrammatically an arrangement in which an electric servo motor is controlled by a follow up switch to achieve positional correspondence between an input handle and an output shaft. A

Figs. 2 and 3 show the detail'arrangement of the follow up. switch indicated diagrammatically in Fig. 1 and show also the electrical circuit in tion on the line S-S of Fig.` 2. 1

Figs. 4 Vand 5 show the application of the invention to a different type of follow up switch which *can be employed in the arrangement shown in shaft '8 and an output shaft E..

" As indicated in more detail in Figs. 2 and 3, the

rvinput member- A consisting of c. hollow cylinder integral with the input shaft 6 and'carrying a or .rintheiorm vof. a bar with two contact surfaces radially extending insulated contact member AX uAI` and A2 on opposite sides. This contact member is connected by a flexible wire A3X to the slip ring- A3' which cooperates with a brush iAl connected to a collector brush A5 of the servo motor I shown as a D.C. motor.`

The output or follow up member B consists of I a hollow cylinder sleeving the member A and integral with the output shaft The follow-up member B carries a radially extending insulated switching dei decelerates, whereupon,

contact member BX in the form of s. bar having two opposite contact surfaces BI and B2 and connected by a flexible wire B3X to a slip ring lrBi cooperating with a brush B4 which is connected to the opposite commutator brush B6 of the motor I.

Between the two members A and B there is interposed a Boating member CD which carries four insulated contact members with contact surfaces CI, D2 between which bar AX projects and C2. DI between which the bar BX projects.

The contacts CI, C2 are both connected by flexible wires CIX and CZX respectively to slipring C3 cooperating with brush C4 while the contacts DI, D2 are connected by flexible wires DIX and D2X to slip ring DI cooperating with brush DI. The brushes Cl, D4 receive the two poles of an electric D. C. supply.

The contact surfaces are so adjusted that when the floating member CD is in its central position there is an air gap between all of the cooperating contact surfaces suiilcient to provide insulation against the voltage of the circuit.

The operation of the switch is as follows:

When the controlling or input member A moves clockwise in Fig. 2, the contact surface AI on the contact' member AX first makes contact with contact CI on the floating member CD and then by driving the floating member CD presses the contact surface DI on the floating member-against the contact surface BI on the bar BX. Equal pressure is thus transmitted through both pairs oi' contacts. A circuit is now established from the positive pole of the electric D. C. supply through brush C4, slip ring C3, flexible wire CIX,

contact surface CI, contact member AX, flexible Wire ASX, slip ring A3, brush AI. brush B4, slip4 f ring B2. flexible wire 33X, contact member BX, contact surface DI, flexible wire DIX, slip ring D3 and brush DI to the negative pole of the electric D. C. supply oi' the servo motor I. The motor l now starts rotating, its polarity being assumed to be such that it drives the output member B andshaft lin the same direction in which the input shaft has been moved. As soon as the motor overtakes the input drive the contacts separate, the circuit is interrupted and the motor provided the input shaft l continues to rotate a new contact is made and so on.

` Following the movement of the controlling member A in the opposite direction it will be observed that the polarity of the fcollector' brushes is reversed whereupon the servo motor I starts its movement in the opposite sense.

In each case the deceleration of the servo motor upon interruption of its circuit may not be quick enough and the output member B of the switch may continue to overtake the input member A until the reverse circuit is established which would generate a strong braking torque until the deceleration is suiiicient for the input member to overtake the output member again and re-establish the driving torque.

In the embodiment shown in Figs. 4 and 5 which can also be employed in the arrangement shown in Fig. 1 the actual current carrying elements of the device are stationary, and all slip rings and brushes are avoided.

The reaction torque on the planetary member P in an epicyclic gear train is used to effect the switching operation of a change over switch. This reaction torque ls dependent on the direction of the relative motion between the input and any purpose and type output `gear and can therefore be used to iiutuate a reversing switch in a follow up niechariiism.

In this embodiment 5 indicates as before `the input shaft and 6 the output shalt coupled through an epicyclic train to shaft i5. The end of the input shaft B has an enlarged portion E formed integrally therewith. The enlarged portion E has a central recess Elv forming a bearing for an end 5i of the output shaft 5, and a flange portion terminating in a ring gear E2. `A sun gear 52 is formed integrally with the output shaft 5 and meshes with planetary gears F and FI mounted for rotation on studs G and Cil firmly anchored in a planetary member P mounted for rotative movement about the output shaft 5. The planetary gears F and FI mesh with the ring gear E2. Planetary member P carries an insulated contact AX' having contact surfaces AI' and A2', while the floating member CD is provided with four contacts CI', C2' and DI', D2'

` as in the previous embodiment.

- B5' of servo motor I, contact BX. contact face BI and contact member DI to the. negative pole of the electric D. C. supply, to start rotation of the servo motor until the motor causes the output shaft B to overtake the input shaft 5, when the planetary member P will be rocked back and lnterrupt the motor circuit. It will be seen that apart from the mechanical arrangement of the follow up switch, the circuit connections are identical with those of Fig. 2.

Inverse rotation of the input shaft will operate contact pairs C2', A2 and D2', B2 and complete the motor circuit with reversed polarity.

The epicyclic gear mechanism used for operating the follow up switch can be of the simple or compound type and since only a very small movement is required the pivot centre of the planetary member P may not coincide with the sun centre at all.

It will be ui erstood that the invention is not limited to the ses described in the accompanying drawing.. van be applied to contact members oi' any to v form, to switches for cult. The actuating mechanism can be made suit any requirement oi' operation. The movement of the floating member can `be rotative or rectilinear and any number of circuits can be controlled by additional floating members.

In my Patent No. 2,387,174 I have demribed and claimed a braking mechanism for an electric motor comprising a brake member connected to the motor shaft for rotation thereby, an electrocome ber when the electric motor is disconnected from the supply of electric current. but saiciflrst-4 `of electric current to said first-mentioned coil is interrupted, and in which the supply of electric current to the motor includes a first member. -a second member, a member floating between said rst and -second members, and electric contact surfaces carried by said first and second members and the oating member for completing an elec# tric circuit to the motor when either the first or second member is moved a predetermined distance relative to the other. herein to the arrangement claimed in my said patent. Subject to this disclaimer, the invention claimed herein is set forth in the appended claims. v

I claim:

l. An electrical switching device comprising a rst movable contact-carrying member, a second movable contact-carrying member, said members being mounted for movement relative to one another, the first contact-carrying member having a contact surface which also serves as a movement limiting and a motion transmitting surface, said second contact-carryingmember having a contact surface which also serves as a movement limiting and a motion transmitting surface, at least one floating member located in the path of movement of the contact surfaces of said ilrst and second contact-carrying members, said floating member having contacts adapted to be engaged by the contacts of said first and second contact-carrying member, the respective parts being so constructed and arranged that when one of the contact-carrying members is moved in one direction relative to the other contact-carrying member, the contact surface of the floating member will be in engagement with the contact surfaces of said first and second contact-carrying members and the oating member will between said contact-carrying members and afford means for imparting movement from one contact-carrying member to another contactcarrying member.

2. An electrical switching device comprising a first movable contact-carrying member, a second I make no claim.

be locked movable contact-cmwing member. said members being mounted for movement in opposite directions relative to one another, each of said contact-carrying members having contactsurfaces on opposite sides which also serve as movementlimiting and motion-transmitting surfaces, and at least one floating member .having portions located in the path of movement of the contact surfaces of said first and second contact-carrying members, said floating member having contacts on said portions adapted to be engaged by the lcontacts on the first and second contact-carrying members. the respective parts being so constructed and arranged that after one of the contact-carrying members has moved a limited amount in either direction relative to the other contact-carrying member a contact surface of said contact-carrying member will engage the cooperating contact surface of the floating mem ber and thereafter move the floating member until a contact thereof engages the cooperating contact of the other contact-carrying member, after which the floating member is locked between the two contact-carrying members and serves as a motion-imparting means between said contact-carrying members, the floating member floating freely between the contact-carrying members when contact surfaces carried thereby are not engaged by the contact surfaces of either contact-carrying member.

3. An electrical switching device as set forth in claim 2 in which the first-mentioned contactcarrying member closes two alternate pairs of contacts at each end of its free movement relative tothe floating member and at least one pair of said alternate pairs of contacts when in an intermediate position relative to the floating member, and in which connections extend from the respective contacts of the contact-carrying members and the Boating member to commutate two poles of an electrical supply with two terminals of an electrical device.

4. An electrical switching device as set forth in claim 2 in which the contact carrying members and the floating member are mounted for rotary movement in opposite directions about a common axis.

GEORGE OLAH. 

